A dye-sensitized solar cell is a photoelectrochemical solar cell originally invented by Grätzel et al. in Switzerland in 1991. Generally, it includes photosensitive dye molecules capable of creating electron-hole pairs, a transition metal oxide used for transport of electrons generated, an electrolyte, and electrodes positioned on both sides.
The dye-sensitized solar cell has advantages over the existing silicon solar cells, such as its simple and eco-friendly manufacturing process and low production cost per electricity generated by it. The conventional dye-sensitized solar cells are, however, prepared using a liquid-state electrolyte and are thus disadvantageously poor in reliability and long-term stability due to leakage or volatilization of the electrolyte.
As one of the solutions to this problem, a dye-sensitized solar cell using a solid-state amorphous and polymer electrolyte as a hole-transporting material has been suggested [Bach, U. et al., Nature 395, 583-585 (1998)].
However, the solid-state electrolyte has such a high viscosity that it cannot be sufficiently filled in gaps formed between semiconductor particles constituting the photoelectrodes in the manufacture of the dye-sensitized solar cell. Such a limited fill efficiency of the electrolyte leads to a difficulty in making the photoelectrodes thick, consequently with deteriorated light-to-energy conversion efficiency and poor reproducibility based on the process environments.